Spike protein region (aa 636-789) of Porcine epidemic diarrhea virus is essential for induction of neutralizing antibodies

To analyze antigenic structure of the spike (S) protein of Porcine epidemic diarrhea virus (PEDV), the gene encoding its major immunodominant region S1 was amplified by PCR. We prepared four truncated S1 proteins spanning the entire S1 domain fused to GST protein. To identify the most important antigenic region of S1, the truncated S1-GST fusion proteins were examined for their ability to react with immune serum against PEEN and to elicit the formation of neutralization antibodies in immunized animals. We found that the region of S1 signed as SID (aa 636-789) was able to react with PEDV antiserum and to elicit formation of neutralization antibodies in mice. Moreover, the immune serum against SID showed the binding ability to the native S protein of PEDV.